Control valve mechanism for pumping assembly



D. C. ELVES April 21, 1959 CONTROL VALVE MECHANISM FOR PUMPING ASSEMBLY Filed Dec. 14. 1955 3 Sheets-Sheet 1 W A? MW) m J j. m H T :JTI 6 I win r a b.

ATTORNEY D. C. ELVES A ril 21, 1959 CONTROL VALVE MECHANISM FOR PUMPING ASSEMBLY 14, 1955 3 Sheets-Sheet 2 Filed Dec.

. [nuZ nio'r': M20: Charles Flues QeLx. 5 7% 2,882,870 CONTROL VALVE MECHANISM FOR PUMPING ASSEMBLY Filed Dec. 14, 1955 D. C. ELVES April 21, 1959 3 Sheets-Sheet 3 k lllmm Rm m, I WW 1 1 H I D I 1 m QQ P- @w F T 7. WA? %n W m M ,QN MN QW aw [nuenio-noaylas Charles Elves flaw/29y.

United States Patent CONTROL VALVE MECHANISM FOR PUMPING ASSEMBLY Douglas Charles Elves, Edmonton, Alberta, Canada Application December 14, 1955, Serial No. 553,150

1 Claim. (Cl. 121-164) This invention relates to control valve mechanism for a hydraulically operated pumping unit, more particularly for use in association with bottom hole pumps of oil wells.

In the operation of an oil well, the bottom hole pump, i.e., the pump at the bottom of the well, is operated by reciprocating a string of pump rods. The means for reciprocating such pump rods is connected to the top pump rod, conventionally called a polish rod.

A general object of the present invention is to provide a more eflicient and satisfactory means for controlling the reciprocation of the pump rods.

A more specific object is to provide controlling mechanism for a pumping unit of the type set forth which is capable of producing an increased length of stroke of the pump rods, thus permitting greater volumetric efficiency in the bottom hole pump, reduction in the number of rod reversals required for any given amount of production, and consequent reduction in localized wear between tubing and rods. Another object is to provide improved means for cushioning or causing gradual rod reversal to reduce the amount of fatigue which occurs during change in direction.

Other objects, details and advantages of the invention will become apparent as this description proceeds with particular reference to the accompanying drawings, in which Figure l is a diagrammatic view of the hydraulic circuit of a pumping unit in accordance with the invention,

Figure 2 is a side elevation of a cylinder and piston assembly for reciprocating pump rods with associated control mechanism in accordance with the invention,

Figure 3 is a front elevation, partly in section, of the structure shown in Figure 2,

Figure 4 is a plan view, partly in section, of a pilot valve trip assembly,

Figure 5 is a sectional elevation of the assembly,

Figure 6 is a sectional elevation of the pilot valve,

Figure 7 is a sectional elevation of a main control valve, and

Figure 8 is a transverse sectional view of a portion of the main control valve.

Referring to Figures 2 and 3 of the drawings polish rod reciprocating mechanism is shown in association with a polish rod 3 of conventional pumping equipment. The polish rod reciprocating mechanism may be mounted on legs 4 and comprises a pair of upright closed cylinders 5. Cylinders 5 are fixed together in parallel relation by means of a lower casting 6 and an upper casting 7. The lower portions of the cylinders are in communication with each other by means of a passage 8 in the lower casting. A piston rod 12 extends through the top of each cylinder and carries at its lower end, within the cylinder, a piston or plunger 16. The upper ends of the two piston rods 12 exteriorly of the cylinders are connected by means of a beam 19.

pilot valve trip As shown, the cylinders 5 are arranged for disposition on either side of the polish rod 3, which extends through castings 6 and 7 and beam 19. Clamped to the polish rod above beam 19 for engagement thereby is a block 20.

Means are provided for hydraulically imparting a succession of upward strokes to the pistons 16 and consequently polish rod 3 and for permitting an alternate succession of downward strokes of the pistons and polish rod. Do this end, the passage 8 is connected by means of a pipe 21 to a source of hydraulic fluid under pressure which may include, as shown in Figure 1, an accumulator tank 22 and a booster pump 23. The control means in accordance with the invention includes a main valve 24 and a pilot valve 25.

The main control valve 24 has a chamber 26 with which pipe 21 communicates through port 27. Chamber 26 has a passage 28 communicating through port 29 and pipe 30 with the suction inlet of pump 23 and a passage 31 communicating through port 32 and pipe 33 with the discharge outlet of pump 23. A spool 34 is reciprocally mounted in valve 24 and, as shown, is arranged to close one of passages 28 and 31 while opening the other to place chamber 26 in communication either with the suction side of discharge side of pump 23. Valve 24 also has a chamber 35 communicating through port 36 and pipe 37 with accumulator 22. It will be observed that spool 34 also places chamber 35 in communication only with the suction side of pump 23 through port 29 .and pipe 30 when passage 28 is closed and in communication only with the discharge side of pump 23 through port 32 and pipe 33 when passage 31 is closed.

The ends of spool 34 reciprocate in cylindrical passages 38 and 39 in valve 24, such passages being closed by end caps 40 and 41. Each cap may be provided with an adjustable screw-threaded pin 42, the end of which is engageable by the adjacent end of spool 34 to regulate the stroke of the spool.

Cap 40 has a passage 43 in communication with a port 44 in pilot valve 25 through pipe 45. Passage 43 has a pair of orifices 46 and 47 communicating with passage 38 in the valve. Flow of oil or other hydraulic fluid out of valve passage 38 through orifice 46 into pipe 45 is controllable by an adjusting screw 48 carried by the valve cap. Orifice 47 is normally closed by a spring-loaded check valve 49 which, however, permits flow of fluid under pressure to enter passage 38 from pipe 45.

Similarly cap 41 has a passage 50 in communication with a port 51 in pilot valve 25 through pipe 52. Passage 50 is also provided with a pair of orifices 46 and 47 communicating with passage 39 in the valve. Flow of fluid out of the valve passage 39 through orifice 46 into pipe 52 is controllable by adjusting screw 48. Orifice 47 is normally closed by the spring-loaded check valve 49 which permits flow of fluid under pressure to enter pass-age 39 from pipe 52. I

Booster pump 23 is driven by any suitable source of power. It may be provided with an overload cut-out as indicated at 58.

The accumulator 22 is a pressure vessel in which a supply of hydraulic fluid is maintained under pressure. Pipe 37, connecting valve 24 and the accumulator, is provided with a valve 62 whereby the fluid line may be closed to permit, for instance, draining of portions thereof. A pipe 63, provided with a relief valve 64 connects the accumulator with the discharge pipe 33 of the pump 23.

A tank 65 contains hydraulic fluid at atmospheric pressure. An air cleaner 65a through which air moves freely in and out of the tank may be provided thereon. A pipe 66 connects tank 65 with port 67 of the pilot valve 25. A pipe 68 connects tank 65 with the accumulator 22. A scavenging pump 69 and check valve 70 are provided in pipe line 68. A pilot stop valve .71 is located in a pipe 72 connecting pipe 68 at a point between valve 70 and pump 69 with tank 65. The valve 71 is arranged for actuation by pressure in. the accumulator through a conduit 73. A line 74 connects. a. port 75 in the pilot valve 25 with the accumulator.

A by-pass line 89 connects passage 8 through the valve 90 to tank 65'.

Pilot valve 25 is. a. conventional four-way pilotvalve having a plunger 76 reciprocable to actuate the valve spool. 59 and place ports 4.4, 51,. 67 and. 75 in selected communication. Valve 25. is supported upon the top casting 7 inassociation with trip mechanism therefor now to be described.

Plunger 76 projects through .a slot 77 in a tubular housing 78 having its upper end fixed to upper casting 7 and its lower end fixed to lower casting 6. Reciprocally mounted in housing 78 is a rod 79 having a lateral extension 80. on its upper end fixed to the piston rod beam 19. A sleeve 81 is slidingly supported on rod 79 within the housing 78 between adjustable means such as upper and lower nuts 82 and 83 on the rod. It will be apparent that the lower end of the sleeve is engageable by nut 83 and the upper end by nut 82 to impart reciprocating movement to the sleeve, the extent of such movement relative to the reciprocating movement of the rod being determined by adjustment of the positions of nuts 82 and 83 on the rod.

As shown in Figure 5, the end of plunger 76 engages or rides upon the external surface of sleeve 81, which has an upper portion 84 of small diameter, a lower por-' tion 85 of large diameter, and an intermediate portion 86 of tapered or gradually increasing diameter connecting portions 84 and 85.

It will be apparent that when plunger 76 engages the small diameter portion 334 of the sleeve, it will be in fullyv extended position and that when it is in engagement with the large diameter portion 85, it will be in fully depressed position. It will further be apparent that transition of the plunger from fully extended to fully depressed position, or vice versa, will be of gradual nature by reason of its engagement with the tapered portion 86.

In operation, with the pistons 16, trip rod 79 and sleeve 81 at their lower extremity of travel, the pilot valve plunger is in its outermost position, in which ports 75 and 44 are connected and ports 51 and 67 are connected. Hydraulic fluid from the accumulator 22 is dischargedto port 75 and passes through the pilot valve to port 44,

thence through passage 43 and orifice 47 into passage 38 in main valve 24, thus causing the valve spool 34 therein.

to move .into the dotted line position of Figure 7. In the latter position, ports 32 and 27 are in communication, and port 29 and 36 are in communication. The fluid contained in passage 39 of the main valve has been forced by spool 34 through orifice 46, thence through ports 51 and 67 of valve 25 to the atmospheric tank 65. The hydraulic fluid. discharged from the booster pump 23- then travels through ports 32 and 27 of the main valve 24 to the cylinders below the pistons, thus causing the latter and the piston rod assembly to rise. The suction side of the booster pump 23 is supplied with fluid through ports 36 and 29 of the main valve 24 from the accumulator during the upstroke. The upward motion of the pistons and associated assembly progresses at a substantially uniform velocity throughout its length to a point at which the pilot valve plunger 76 is depressed by the large, diameter sleeve portion 85 of the trip mechanism.

This actuation of the pilot valve 25 places ports 75 and 51 in communication and ports 44 and 67 in communication. Fluid is thus permitted to flow from the accumulator through port 75 and 51 to. passage 39 in the main valve, 24. Spool 34 is therebly moved into passage 38 and forces fluid through the variably controllable orifice 46, and thence through ports 44 and. 67 to the atmospheric tank 65. The. pressure in passage 39 is equal to that being exerted by the accumulator while. the; back 2 to. that existing in the accumulator.

A: pressure in passage 38 is equal to the resistance imposed on the flow of fluid through the controlled orifice 46 Thus, the pistons travel downwardly in the cylinders to efiect, with their associated elements, a downstroke preparatory to a succeeding upstroke.

In its travel, the spool 34 first simultaneously causes the throttling of the fluid flow trom port 32 to port 27 while opening ports 32 to port 36, and then throttles fluid flow from port 29 to port 36 while opening ports 27 to port 29. Thus, the upward travel of the pistons is gradually arrested, and the downward travel of the pistons commences gradually while increasing to a maximum speed when the valve spool travel has'been completed. A similar sequence occurs at the bottom of the stroke, in which the downward velocity is gradually arrested prior to reversal and the upward velocity gradually increases following reversal. The rate of change of direction of the pump rod string can, therefore, be varied to reduce the stress on the rods to-a minimum.

The scavenging pump 69 receives fluid at itssuction. from the atmospheric tank 65 and normally discharges the fluid through pilot stop valve 71 to the tank 65. Should, however, pressure in the accumulator fall below apredetermined degree, such pressure drop is transmitted to valve 71 through conduit 73 to close valve 71. Fluid fiom the pump 69 is then discharged t-othe accumulator. through check valve 70 until the accumulator fluid volurne is restored, and the pressure returns to the predetermined level. When this occurs, the pilot stop valve 7L opens and the normal cycle resumes.

Should the pressure in the discharge line 33 of the booster pump 23 become excessive for any reason, relief valve 64 opens and allows fluid to pass to the accumulator.

The bypass line 89 permits draining of fluid from the cylinders. To effect this, valve 62 is closed and thevalve 90' is opened allowing fluid to flow into tank 65.

The overload cutout 58 may comprise an electrical switch actuable by pressure-operated mechanical means: The cutout switch is located in a control circuit for themotor or other power source. If the pressure required to actuate the pump pistons becomes excessive, or if the suction pressure from the accumulator drops off becauseof oil or gas leakage, the cutout switch is actuated to cut off the power supply.

The conditions under which the counterbalance effect of the mechanism takes place may be inferred from the foregoing description. However, these conditions may be summarized as follows:

During the downstroke the weight of the rods exerts hydraulic pressure on the fluid in the cylinders. This fluid is withdrawn through the valve to the'boosterpump and its pressure is increased to discharge pressure equal At the beginning of the downstroke the accumulator pressure is equal to that imposed by the dead weight of the rods on the-cylindersand there is theoretically no boost pressure. As the oil volume in the accumulator increases, the pressure increases to a maximum at the bottom of the stroke, such maximum pressure being equal to that required to raise the. pump rods and fluid at the commencement of the upstroke. Accordingly, the booster pump does not increase the pressure of the oil being delivered to the cylinders at the start of the upstroke, however the boost increases from zero to a. maximum at the top of the stroke when the accumulator has become depleted.

The mechanism described may also be used as a nonconnterbalanced unit. The non-counterbalance pump would have one atmospheric tank from which fluidv would downstroke. An appropriate change in the valvev spool is required to convert valve 24 to non-counterbalance AMA:

operation. Such a non-counterbalance unit is simple and very suitable for the pumping of shallow wells.

I claim:

In a pump rod reciprocating assembly having a source of pressure, a hydraulic fluid line and a hydraulic fluid circuit each connected to said source of pressure, a pair of parallelly arranged upright cylinders, a piston in each said cylinder having a piston rod, a beam connecting said piston rods together for simultaneous movement, said hydraulic fluid line communicating with the space below said pistons in both said cylinders, a main control valve in said line and circuit and operable to divert fluid from said line to said circuit to permit a downward stroke of said pistons and beam, a pilot valve mounted on said cylinders adjacent the upper end thereof and having an operating plunger, said pilot valve being hydraulically connected to said main valve to actuate said main valve,

and trip mechanism for operating said pilot valve comprising a trip rod fixed to said beam and reciprocal therewith, a sleeve on said trip rod and having adjustable reciprocating movement therewith, said sleeve being in engagement with said plunger and having an enlarged diameter portion arranged to depress said plunger on engagement therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,966,739 Shappell July 17, 1934 2,019,353 Lower Oct. 29, 1935 2,185,448 Suter Jan. 2, 1940 2,232,449 Habenicht Feb. 18, 1941 2,347,302 Twyman et a1 Apr. 25, 1944 2,564,285 Smith Aug. 14, 1951 

